Reiterating percussive effect apparatus for electronic musical instruments



Dec. 15, 1959 J. M. HANERT I REITERATING PERCUSSIVE EFFECT APPARATUS FOR ELECTRONIC MUSICAL INSTRUMENTS Filed June 21. 1955 RUR 2 E: a O H PA 4 A 'Ilk m IIOV- A- TSG United States Pate-nt O REITERATING PERCUSSIVE. EFFECT APPARATUS FOR ELECTRONIC MUSICAL INSTRUMENTS John M. Hanert,Des Plaines, Illt, .assignjor to Hammond Organ Company,iChicago, 111., a 6013130111110 of Delaware Application June 21, 1955, Serial No. 516,977

4 Claims. (l.:84f-1.26)

The invention relates generally to electrical musical instruments andmore particularly tormeans whereby an instrument of this character may be made to sound a tone reiteratively, with percussionenvelopes, as -long as the playing key controlling. such tone. is held depressed.

In the rendition of some types-.zof music it is highly desirable tobe able to play. reiterative percussive tones. For example, in' playing. fastmandolin or banjo type of music the reiterationrate "is rso rapid that it cannot be attained on a keyboard instrumenL-either because of the slowness of response of the'instrument, .or because of lack of sufficient skill on the part. of the player.

The invention therefore 'comprisesmeans for introducing a rapid iterative percussive .efiect- .commencing immediately with'the depressionofa playing key and continuing as long as the playing. key is held depressed.

Theprimary object of the invention .is' to provide a self-operatingreiterative device for producing rapidly repeated percussiontones whose reiterations are caused to commence coincidentally with the depression of a playing key.

A primary object of the invention.istoproduce an instrument. whereby reiterative percussive tones may be easily rendered by theuplayer without requiring great skill on his part and'without unduly tiring the musician, and in which the first of a series of reiterativepercussion tones is sounded simultaneously with the depression of thekey.

A further object is to provide. a reiterative percussion apparatus which is always in condition to start operation without delay upon depression ofa key.

Other objects willkappear frornvthefollowing description, reference being had to the accompanying drawing which shows a schematic circuit and-'blockdiagram of an instrument incorporating the invention.

In the drawing a generator is conventionally illustrated-as representing any. of the usual sources of electrical musical tone signal generators which may be any of several types of rotating or vibrating signal generators, or electronic. oscillators and the like. In a polyphonic instrument each of the keys 12 of the keyboard will be adapted to close a switch 14 upon depression of a key. In other forms of the invention such as in a solo or monophonic instrument the generator may be permanently connected to the output of the instrument and either tuned to the desired frequency or rendered operable as by keying current to the anode of an electron discharge device which forms part of an oscillator.

However, as shown, the key switch 14 connects the generator to the primary L16 of a matching transformer T17 through a decoupling resistor. R18. The secondary L20 of this transformer has its end terminals connected respectively to the control grids of control pentodes 24 and 26. The anodes of these pentodes are connected to theprimary of an output transformerTBO, the secondary of whichis connected to a power amplifier 32 which supplies a speaker 34. The anodes of the pentodes 24 2,916,957 Patented Dec. 15, 1959 ICC and- 26 are supplied-with current from a suitable source indicated as +285. v.' connected to the center tap of the primary of transformer T30. The screen grids are connected-to a source of operating: potential indicated as a terminal +40..v. The. cathodes of these pentodes are connected to a conductor 40 which is connected to ground through a capacitor C42. A voltage divider comprises a resistor R44, connected between a +285 v. terminal and a terminal 46,.and a resistor R45, connected between said terminal 46 and ground. The terminal 46 is connected to. the conductor 40 by a resistor R48. The resistor R45. is adapted to be shunted upon closure of a switch 50 operated by the playing .key 12. This switch is arranged to be closed slightly after the closure of switch=14 upon the depression of the playing key. The

resistors R44 and R45 are of such relative value that: a potential of about +35 .volts is maintained on the terminal 46 when the switch 50 is open. A center tap 52 on the secondary L20 is. connected to ground by a capacitor C54 and ismaintained at a potential of approximately '+5 volts, when the switch 50 is open, by a rectifying system now to be described.

Thereis connected to the power supply input transformer T56 a secondary L57 which operates as an isolated low power voltage source. The transformer sec ondary L57 has one terminal connected to the plate of a rectifying diode 58 and another terminal connected to theanode of this diode through a load resistor R60 and a filteringcapacitor-C62. Thus the diode will generate a direct current potential difference across the resistor R60 of approximately 3.5 volts. An anti-spark resistor R64 connects one terminal of the resistor R60 to the anode of-a diode 66 thecathode of the latter being connected to the +5 volt terminal of the power supply. This diode 66 operates as a voltage limiter to maintain a voltage of +5 volts upon the plate of another diode 68 the cathode of which is connected to the center tap 52 of the secondary L20, and is connected to 21-30 v. terminal through a relatively high impedance discharge resistor R70.

A low frequency vcathode coupled oscillator comprising triodes 74 and 75 'hascomponents connected thereto to cause the oscillator to operate at a reiteration .frequency of approximately 7 c.p.s.' A feedback capacitor C76 is connected between the anode of triode 75 and the grid of the triode 74 the latter being also connected to ground through a grid return resistor R78. Terminals B+ of the power supply are connected to the plates of the triodes 74 and 75, the connection for the triode 75 being made through a load resistor R80. The cathodes of these triodes 74 and 75 are connected to a conductor 82 which is also connected to the cathode of the previously mentioned: rectifier diode 58. The conductor 82 is connected to a terminal 46 through a common cathode resistor R84.

In operation, with no key depressed, a fixed bias of approximately 37 volts derived from the voltage divider R44, R45 appears on the cathodes of the control tubes 24 and 26 and maintains them in cutofi condition. This +37 volt potential is supplied through conductor 82 and resistor R84 to the resistor R60 and is there opposed by the approximately 30'volts generated by the ungrounded supply (comprising transformer secondary L57, diode 58, and capacitor C62) so that the voltage at the resistor R64 will be about +7 volts. This voltage appearing on the anode of the diode 66 is reduced to +5 volts because the cathode of this diode 66 is connected to a +5 v. terminal of the power supply. The 30 v. terminal of the power supply being connected to the cathodes of the switch diode 68 through the high value resistor R70, the control grids of the pentodes 24 and 26 are maintained at about +5 volts due to low impedance of +5 volt supply circuit.

When a key is depressed the potential on the cathodes of the control tubes 24 and 26 drops from about +37 volts to about +5 volts by virtue of the closure of a switch 50, thus allowing the control tubes 24 and 26 to conduct the signal. This also reduces the potential upon the anodes of diodes 66 and 68 to substantially 30 v. making them both non-conducting. This effectively isolates the control tube grids from the switch diode 68 and the diode 66. The voltage on the grids of the pentodes 24, 26 will drop to 30 v. as fast as the capacitor C54 can be charged to -30 volts through the decay resistor R70. If desired the resistor R70 may be made effectively adjustable to permit variation of the decay time.

Closure of the switch 50 also results in causing an operating potential to exist between the cathode and plate circuits of the oscillator comprising the triodes 74 and 75. This oscillator then immediately commences oscillating and at intervals of approximately one-seventh, or one-eighth of a second, these pulses being effective to raise the potential on conductor 82 to a value of approximately +37 volts thereby again causing the +5 volt potential to appear on the cathode of the switch diode 68 and upon the control grids of the pentodes 24 and 26, thus conduction at a high level is reestablished through the control tubes.

The essence of the invention may be better understood by considering the operation of the apparatus if the oscillator comprising triodes 74 and 75 were operating continuously in the manner of a pipe organ tremolo. Under these conditions, the switch 50 and associated circuits would not be present and the initial percussive tone would not necessarily be produced upon the instant of closure of the switch 50 but, depending upon the instantaneous phase of the output of the oscillator, would usually commence some time after key depression. In fact, in some cases, if the key is played staccatowise the control pentodes may be cutofi at the instant of the key depression and no tone would be produced. With the apparatus of this invention a reliable percussion tone of at least one reiterative stroke will always be produced for short staccato depressions of the playing key 12. It is the control of both the signal and the reiteration oscillator apparatus by the playing key which insures this reliability of reiterative tone production.

In essence the invention comprises an intensity envelope control means capable of causing the tones to be produced with a percussive envelope, feedback circuitry coupled to the intensity control means but normally ineffective to cause operation of the percussion intensity envelope control means, and means operable by the key to cause a signal from an electric tone signal generating means to be supplied to the intensity envelope control means and at the same time to initiate a percussive intensity envelope cycle either directly by the key operation or through initiation of the operation of the feedback circuitry, and thereafter, while the key is held depressed,

4 reliably to initiate the first reiterative stroke upon depression thereof, and further permits the self-reiterating apparatus to produce reiterative percussion tones during the period of time that a playing key is held depressed, without further effort on the part of the player.

While I have shown and described a particular embodiment of my invention, it will be apparent to those skilled in the art that numerous modifications and variations may be made in the form and construction thereof, without departing from the more fundamental principles of the invention. I therefore desire, by the following claims, to include within the scope of my invention all such similar and modified forms of the apparatus disclosed, by which substantially the results of the invention may be obtained by substantially the same or equivalent means.

I claim:

1. In an electrical musical instrument having an electrical tone signal generating means, a playing key, an output system including a tone intensity envelope controlling means operable upon application of an electrical pulse thereto to cause tone signals from the generating means to be transmitted by the output system with a percussive intensity envelope, means operable upon depression of the playing key to cause signals from the generating means to be supplied to the output system, means to supply an initial pulse to the envelope controlling means upon depression of the key, a reiteration oscillator av operable at a frequency of about 7 cps. and rendered operative to commence oscillating at the reiteration frequency by the depression of the playing key, and means coupling the oscillator to the tone intensity envelope controlling means to cause the oscillator to supply subsequent pulses to the envelope controlling means and thereby cause the latter to produce percussive tones in rapid succession following the percussive tone produced by the initial pulse upon depression of the playing key,

said percussion tones thereby reiterating as long as the key is held depressed.

2. In an electrical musical instrument for the production of reiterative percussion tones, the combination of an electrical tone signal generator, a percussion intensity rendering the feedback circuitry effective to cause reiterative percussion cycles of the intensity envelope control means.

From the foregoing it will appear that the particular circuitry disclosed in this application is not essential to accomplish the purposes set forth in the preceding paragraph but that there may be wide variation in the particular means employed. The circuit disclosed herein has been found however to be practical and effective to accomplish these purposes.

Further, the reiteration oscillator comprising triodes 74 and 75 may be continuously operating but also be supplied with a triggering pulse due to closure of switch 50, in a manner well-known to the electronic art, to initiatea new chain of oscillations the first of which is related to the instant at which switch 50 is closed. Under these circumstances the operation would be like that of the apparatus shown and described. The important features of the invention is that the playing key is effective envelope control means, a playing key for causing said generator to impress a continuous audio frequency signal at the input of said intensity envelope control means while the key is held depressed, means operable immediately upon depression of the key to cause operation of the percussion intensity envelope means, an electroacoustic translating means coupled to said percussion intensity enevelope control means, feedback means associated with said intensity control apparatus for causing self-induced oscillations to produce corresponding reiterative percussive variations in intensity at the output of the intensity envelope control apparatus, and a coupling between said playing key and said feedback means whereby depression of said playing key is operative to render said feedback means effective, thereby to cause a reiterative percussion tone whose first reiterative stroke is reliably initiated by the operation of the playing key and whose subsequent reiterative strokes are caused by the self-induced intensity variations in the intensity envelope control means by the feedback means.

3. In an electrical musical instrument for the production of reiterative percussion tone effects, the combination of a playing key, an intensity envelope controlling apparatus, a tone generator, a coupling between the tone generator and the envelope controlling apparatus made effective by depression of the playing key, an auxiliary reiteration device, a coupling between the playing key and the auxiliary reiteration device, a coupling between the reiteration device and the intensity envelope controlling apparatus, electroacoustic translating means coupled to the intensity envelope control apparatus, and means controlled by depression of the key for causing the reiteration device to commence oscillations coincident with the operation of the playing key, thereby to cause a reiterativc percussion tone whose initial reiterative stroke is reliably initiated by the operation of the playing key and whose subsequent reiterative strokes are caused by the oscillations self-induced by the reiteration device.

4. In an electrical musical instrument for the produc tion of reiterative percussion tones, the combination of a playing key, intensity envelope controlling apparatus, an electrical tone signal generator, a first coupling between the tone generator and the input of the intensity envelope control apparatus which is made efiective by depression of the playing key, an electroacoustic translating means coupled to said intensity envelope control apparatus, feedback means coupled to said intensity con- 15 2,485,538

trol apparatus for causing self-induced oscillations to procluce corresponding reiterative percussion type variations in intensity at the output of the intensity envelope control apparatus, and a second coupling between said playing key and said intensity envelope control apparatus whereby operation of said playing key is operative reliably to initiate a first reiterative stroke simultaneously with the depression of the key, subsequent reiterative strokes being caused by the self-induced intensity variations in the 10 intensity envelope control means by the feedback means.

References Cited in the file of this patent UNITED STATES PATENTS Ranger Mar. 21, 1933 Rowe Oct. 18, 1949 

